The Buddies extended their impressive unbeaten home run to double figures after battling to a point against Hearts.
St Mirren raced into an early lead when Ryan Strain's powerful free-kick nestled in the bottom corner, aided by a deflection off the defensive wall.
The home side dominated the first 45 and should have added to the lead before the break, with Alex Greive spurning two excellent chances and Curtis Main also going close.
